In pursuit of economic growth, energy demands are dramatically increased day by day. However, available fossil fuel is dwindling. In the foreseeable future, human will face increasing energy cost and energy shortage as well as other problems. Moreover, as the regulations of environment quality are increasingly stringent and the emissions of greenhouse gases (mainly carbon dioxide) catch more and more world's attention, the needs of high-performance, new and clean energies are gradually urgent. Therein, solid oxide fuel cell (SOFC) is one of the most promising clean energies, because it has the advantages of high efficiency of power generation and low rate of carbon dioxide emission.
According to the source materials, hydrogen can be produced through reformation with natural gas, petroleum, coal and electrolytic water, where natural gas is the main source material for hydrogen production. Abundant natural gas has been reserved (about twice to the current total global reserved organic carbon of fossil fuel) so that they are likely to become the most important energy resource in 21st century. For now, all countries in the world scramble in researching and developing hydrogen energies produced with natural gas for obtaining a place in grasping enough energy in the future. Therein, the main component of natural gas is methane (CH4), whose content is about 85˜95 percents and methane is the hydrocarbon having the highest hydrogen ratio. Thus, methane can produce the highest ratio of hydrogen.
However, the traditional hydrogen production by steam reformation is complex and takes space. Hence, the complexity of the equipment needs to be simplified and catalyst performance has to be improved. When reactions are processed at high temperature by a reformer with nickel-based catalyst granules filled, there are problems occurred, like big pressure drop, poor thermal conductivity, catalyst granules easily broken owing to thermal stress impact, etc. Moreover, carbon deposition will cover activity center of catalyst surface and block channels, where the catalyst may even be powdered to further affect power generation of the fuel cell. Rostrup-Nielsen and Hansen studied carbon deposition ratios of different metal catalysts (Rostrup-Nielsen, J R, Hansen, J H B, J. Catal. 144 (1993) 38). After the reaction of CH4/H2=95/5, the carbon deposition results were obtained by measuring through thermogravimetric analysis (TGA) as shown in FIG. 2, where serious carbon depositions by nickel were confirmed.
A prior art revealed in 2003 used a hydrogen-rich gas as a fuel for SOFC after hydrogen was produced by steam reformation with natural gas. Another prior art of a methane reformer for SOFC used nickel-based granules with a carrier of γ-alumina oxide (γ-Al2O3) to produce hydrogen by steam reformation. Yet, carbon deposition would appear; the catalyst might be powdered after the steam reformation; the hydrogen-rich gas produced at back end could cause pulse voltage drop with current instability; and, even more, catalyst dust and carbon deposits would pollute SOFC through gas pipelines and cause system crash.
Hence, the prior arts do not fulfill all users' requests on actual use.